This video should come in handy. I know it’s cracked and you may or may not have a heat mat but a heat gun should do just fine. The factory seal apple uses on these things it pretty tough but you should be able to get it off. https://www.youtube.com/watch?v=HRaxvV051XY&t=633s
Once you get it off, use some acetone and q-tips to get the old adhesive residue off. It’ll help the new screen adhere better.