First you have to cut the foam rubber between the plate and the screen with a cutter, carefully, to avoid damaging the cables. Once the two pieces are separated (pcb and lcd joined by the cable, take care to damage it), you have to apply flux in the pins to proceed to desolder with a soldering iron or heat gun. Remember that the best thing is not to stick the screen to the pcb because the heat could damage it. You can help with pliers to pull the pins, but be careful not to break the contacts of the pins.
By the way, be careful when soldering the pins. Check well which pin is each in the gpio of the lcd (usually is in the page of the manufacturer / seller of lcd