Just take it off before sending it in. You can also send the InvisibleShield back and they will send you a new one if you removed it because of sending it in for service.
Don't sweat the very little water that it takes to get the IS on. It won't hurt the Touch at all.. In fact, when I installed mine, I actually submerged the whole skin under water and let it drip off first before I slid it on. I had no problems and it's a lot easier than trying to squirt it with that little bottle of whatever it is, that they give you..
Do not fear the magical "solution" that comes with the invisible shield. it took me about three tries to successfully align my shield with my touch and it sprayed the hell outta that little piece of plastic in the process. and my lit'l ipod is fine. that shield sure is cool too... i never thought plastic would help so much. so don't worry. your ipod will not be damaged. unless you submerge it. so don't.
Still waiting on mine got it covered with painters tape atm... and they should make the touch water proof.. i can see the and now Touch you pod in the tub LOL