[SalesForce] calculation from input field using visualforce page

Once sure fire way to remove the labels is to put your apex:inputField inside a tag

Like so:

<apex:pageBlockSection id="yearInfoPageBlock" title="Fiscal Year Information">

    <apex:pageBlockSectionItem>
        <apex:inputField value="{!Fiscal_Year__c.name}" onclick="test();"/>
    </apex:pageBlockSectionItem>
    <apex:pageBlockSectionItem>        
        <apex:inputField value="{!Fiscal_Year__c.Is_Current__c}" id="isCurrent"/>
    </apex:pageBlockSectionItem>

</apex:pageBlockSection>

Give it a try!

Oh right.. re-reading your question, that might not be what you are trying to achieve.

If you are trying to "hide" the whole input thing with a bit of Javascript. I would recomment wrapping them in output panels, and then calling "hide" on those.

<apex:pageBlockSection id="yearInfoPageBlock" title="Fiscal Year Information">

    <apex:inputField value="{!Fiscal_Year__c.name}" onclick="test();"/>

    <apex:outputPanel Id="isCurrent"> 
        <apex:inputField value="{!Fiscal_Year__c.Is_Current__c}" id="isCurrent"/>
    </apex:outputPanel>

</apex:pageBlockSection>

<apex:includeScript value="{! $Resource.jQuery }"/>
    <script type="text/javascript">
        function test(){
            $('[id$="isCurrent"]').hide();

            $('[id$="isCurrent"]').hide();
        }
    </script>

Also: are you familiar with the "rendered" tag on all elements, which you can use to control their display (both label and input in the case of form elements) from your Apex controller/other formulaic values?

This is the code that will work with addError methdod

account.NumberOfEmployees.addError('You must enter a value.'); this way you can add error message on field level ..

Page

<apex:page controller="AddErrorCtrl" tabStyle="Account">
    <apex:messages />
    <apex:form >
        <apex:pageBlock title="Hello {!$User.FirstName}!" id="pblock">
        This is your new page for the {!name} controller. <br/>
        You are viewing the {!account.name} account.

        <p>Number of Locations: <apex:inputField value="{!account.NumberofLocations__c}"
            id="Location_validation"/>
        (Enter an alphabetic character here, then click save to see what happens.) </p>

        <p>Number of Employees: <apex:inputField value="{!account.NumberOfEmployees}"
            id="Employee_validation"/>
        (Enter an alphabetic character here, then click save to see what happens.) </p>
            <p />
        <apex:commandButton action="{!save}" value="Save" rerender="pblock"/>
         <p />
        </apex:pageBlock>
    </apex:form>
</apex:page>

Controller

public class AddErrorCtrl {
    Account account;

    public PageReference save() {
        if(account.NumberOfEmployees == null)
        {
            account.NumberOfEmployees.addError('You must enter a value.');
            return null;
        }
        if(account.NumberofLocations__c == null)
        {
            account.NumberofLocations__c.addError('You must enter a value.');
            return null;
        }
        try{
            update account;
        }
        catch(DmlException ex){
            ApexPages.addMessages(ex);
        }
        return null;
    }

    public String getName() {
        return 'MyController';
    }

    public Account getAccount() {
        if(account == null)
        account = [select id, name, numberofemployees, numberoflocations__c from Account
        where id = :ApexPages.currentPage().getParameters().get('id')];
        return account;

    }
}

Updates: Validate fields using Jquery

<apex:page controller="AddErrorCtrl" tabStyle="Account">
    <style>
    .error{ border:1px solid red !important;}
    .messageClass{color: red; display: inline; float: right;position: absolute;margin: 3px;font-size:11px}
    </style>
    <apex:messages />
    <apex:form >
        <apex:pageBlock title="Hello {!$User.FirstName}!" id="pblock">
        This is your new page for the {!name} controller. <br/>
        You are viewing the {!account.name} account.

        <p>
            Number of Locations: <apex:inputText value="{!account.NumberofLocations__c}" id="Location_validation"/>
        </p>
        <p>
            Number of Employees: <apex:inputText value="{!account.NumberOfEmployees}" id="Employee_validation"/>
        </p>
        <p>
            <input type="button" value=" Save " onclick="validateFields();" class="btn"/>
            <apex:actionFunction action="{!save}" name="SaveAF" rerender="pblock" />
        </p>
        </apex:pageBlock>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.3/jquery.js" ></script>
        <script>
            var isValidate = true;
            function validateFields()
            {
                var varFieldlist = ["Location_validation",  "Employee_validation"];
                validateRequiredFields(varFieldlist);
                if(isValidate)
                {
                    SaveAF();
                }
            }
            function validateRequiredFields(arrayFields){
                $.each( arrayFields, function( i, val ) {
                    if($('[id$='+val+']').val() =='')
                    {
                        if(!$('[id$='+val+']').hasClass('error'))
                        {
                            $('[id$='+val+']').addClass('error');
                            $('[id$='+val+']').after("<p class='messageClass' id="+'__'+val+"> Required </p>");
                            isValidate = false;
                        }
                    }
                    else if($('[id$='+val+']').hasClass('error'))
                    {
                        $('[id$='+val+']').removeClass('error');
                        $('[id$=__'+val+']' ).remove();
                        isValidate = true;
                    }
                });
            }
        </script>
    </apex:form>
</apex:page>