How do i remove this light fixture

If you can push the machine screws up, then you can just spin the bottom half of the bracket and get at the screws that are holding it.

If you can't push them up, grab them with locking pliers (ie, visegrips) and spin them out.

If that doesn't work, use brute force to bend the bottom half of the bracket to give you access to the screws holding the top half. Then you'll be in a better position to assess the hanging machine screws.

oh, and so I can sleep well at night, please put a cap on that black wire... you never know who'll flip a switch on you at the wrong time...

Pushing your switches back into the box is causing something to short together - your screws, grounds, or any exposed wire sticking out of backstabs (of which there should be none).

Are you getting intense arc flashes? If you look closely at your screws, grounds, and any exposed wire sticking out of backstabs -- you will probably find arcing marks that will tell the tale.

If you are not getting arc flashes of any size, this part of the circuit may be protected by AFCI or GFCI.

To protect screws, wrap the switch or receptacle with electrical tape so the screws are covered.