From the Kindle Direct Publishing Terms and Conditions:
5 Your Commitment. Your commitment to these terms and conditions is important, and the benefits we provide to you as part of this option are conditioned on your following through on your commitments. If you un-publish your Digital Book, we will remove it from the Kindle Subscription Programs and the Kindle Owners’ Lending Library, but you must continue to comply with these commitments, including exclusivity, through the remainder of the Digital Book’s then-current 90-day period of participation in KDP Select. If you don’t comply with these KDP Select terms and conditions, we will not owe you Royalties for that Digital Book for the Kindle Subscription Programs or Kindle Owners’ Lending Library Programs, and we may offset any of those Royalties that were previously paid against future Royalties, or require you to remit them to us. We may also withhold your Royalty payments on all your Digital Books for a period of up to 90 days while we investigate. This doesn’t limit other remedies we have, such as prohibiting your future participation in KDP Select or KDP generally.
Go to your bookshelf, click on the 3 dots right of your book.
Click on KDP Select Info.
A box will come up, giving you the enrolment dates.
Untick the automatic re-enrolment and await for the date to come and go before publishing anywhere else.
If you can't make sales in Select, you likely won't do any better anywhere else. The first thing to do is to honestly evaluation why you aren't selling, not look for a magic bullet elsewhere. There aren't any.