There are ways to get the water out from under the liner without removing too much from the pool. The easiest is to untuck the liner in the deep end and feed a suction hose behind the liner and hook a pump up to it, with the discharge being sent down the hill from the pool. Probably a better approach is to dig a 'well point' near the deep end and be able to put a pump in that (I can tell you more about them, but basically, it's a hole a couple of feet deeper than your pool bottom in which you put ~ 1' gravel and keep the hole open so you can install the pump and drain the water out from under your pool)

Unfortunately, it's not as simple as just removing the ground water The liner needs to have the wrinkles pushed out as the water under the liner goes down. Sometimes all you need do is aggressively brush the liner as the water lowers - most times, you need to lower the pool water and manually force the wrinkles out

If you go the route of slowly draining the water from behind the liner and are diligent about brushing the wrinkles away - it'll probably be a daylong process - the other way is much more labor intensive, but much quicker for fixing the wrinkles

I can tell you what and how to do what needs be done - whichever way you want to approach this problem and am more than willing to help you

Let me know what you are prepared to do and which way you want to fix this, and I'll be here for you every step of the way