Learn English – word for when someone tells you to do what you’re already doing

You are looking for circumlocution.

Circumlocution (also called circumduction, circumvolution, periphrasis, or ambage) is locution that circles around a specific idea with multiple words rather than directly evoking it with fewer and apter words.

• For example, governmental income support to poor residents might be referred to as "welfare".

• Roundabout speech refers to using many words (such as "a tool used for cutting things such as paper and hair") to describe something for which a concise (and commonly known) expression exists ("scissors").

• The vast majority of definitions found in dictionaries are circumlocutory.

[Wikipedia]

OED definition of "circumlocution: "The use of many words where fewer would do, especially in a deliberate attempt to be vague or evasive".

It's called being contrary:

From Merriam-Webster:

4 : temperamentally unwilling to accept control or advice

From Oxford Dictionaries:

2 Perversely inclined to disagree or to do the opposite of what is expected or desired.
// ‘she is sulky and contrary where her work is concerned’

It's a personality trait that I actually share. (Although in a more specific way than these definitions.) If I'm told to do something by somebody in an authoritarian manner, and there is no rationale for the action, I will very often do the opposite just to make a point—even if the thing is something I would have been inclined to do on my own if I hadn't felt arbitrarily "forced" into it.