You did not give us much information. I see from another post that you owe $23,000, so it seems to be week to use each year for 10 years and you have just over 4 years in payments to make.
The money you paid up front and financed is a totally different deal than RTU - it was the amount you paid to be a member/owner. A Right To Use Contract means that you have the Right To Use a week upon paying your MF. The MF are what you pay each year to actually get to use the unit once you have become a member/owner.
So......
You can stop making payments. You will probably get many calls and letters. It could be a hit on your credit report. Any money you paid upfront will not be refunded. If you go this route, be sure to cancel the Credit Card that you used for the deposit so that they do not use it again.
You would not be able to sell it until it is paid for, so selling is not an option. Besides the transfer fees in the contracts make it impossible to sell. That would be on top of what you owe. (Most likely 10 times the MF.)
Do not use a company that promises to sell your timeshare - that will be another $3000 or so and they will not sell it. These are iffy at best and when you still owe $23,000 + 10x MF it is not going to happen.