1.  Does the listing say it has a pool?  If yes, have the seller change that IMMEDIATELY and print out a new MLS listing without the pool mentioned.

2.   Fill in the pool and landscape over it.   How will the lender know if there was a pool?  Probably can't tell unless they know the history of the house or look at the MLS listing.

3.   The appraiser won't see a pool, so it won't be mentioned in his report.

4.  The inspector wont' see a pool, so it wont' be mentioned in his report.

5.   Tell the sellers NOT to mention that there USE TO BE a pool.

6.  Tell the realtors NOT To mention that there USE TO BE a pool.

I hope all of the above works for you.