Power off the PC, and disconnect the power cable from the tower.

Open the side panel on the PC.

Some panels have clips that are easy to unlatch, and others have screws that need loosening. Only the panel that gives access to the components needs removing.

Remove the screw(s) holding the graphics card into the slot.

Unclip and remove any power cables connected to the GPU.

Release the PCI-e slot tabs that hold the GPU in place.

You may have to unlock it to release the card.