The touchscreen and the LCD are two separate things but attached by a fairly thick two-sided adhesive rubber.
I've always taken off known good touchscreens by slicing the rubber between the panes with a brand new, sharp Exacto blade.
Do NOT cut into the ribbon cable or your fingers!
If you're clumsy with a knife, do NOT even attempt this, as it requires utmost patience and time.
Not all touchscreens have the same wiring pinouts at the Molex connections.
You have to find ribbon cable schematics of the models you're using to get that part right.