Well it's off to YouTube for you!
Find a video of someone removing the cooler from the same model graphics card as yours.
You
still have not properly filled out your system specs; there is no specific mention of your graphics card manufacturer and model. Aftermarket graphics card manufacturers almost always make several product lines (for example, Asus has Phoenix, Dual, KO, TUF Gaming, ROG Strix) that might have the same GPU but will have different PCB form factors and cooler designs.
That means don't watch a video of someone removing the cooler from a Sapphire Pulse Radeon RX 580 if you have an ASUS TUF Gaming Radeon RX 580. The cooler designs will be different, meaning the screws will be in different places and possibly other components like fan cables, etc. If you have an ASUS TUF Gaming Radeon RX 580, watch a video of someone removing the cooler from an ASUS TUF Gaming Radeon RX 580. Don't watch a video of a guy doing it on an MSI RX 560, or a Sapphire RX 550, or an ASUS TUF Gaming Radeon RX 5700 XT.
You will have to be very meticulous about tracking screws.
Also, most graphics card manufacturers use thermal pads on key components that can't have thermal paste applied to them. Ideally you would have some new thermal pads in different thicknesses on hand to replace any original thermal pads that have deteriorated.
When you're replaced all of the thermal interfaces (pastes and pads), you'll need to reassemble your card, meaning reversing all of the steps you watched in the video.
Without a doubt most people who post such videos on YouTube have years -- sometimes decades -- of experience.
Watch the video several times and decide wisely whether or not you have the technical ability to follow the procedure. If you bake cookies and bungle it, you can just buy new ingredients and start a new batch; flour, eggs and sugar aren't expensive. With today's semiconductor shortage situation, it is unlikely you will buy more GPUs until you figure out how to do this.
Best of luck.