My book shelf has been on hold for almost a month due to money issues.

I just took my books off hold so they could be requested.

Problem is one of the books I just got in the mail was listed along with my posted books.

This book was on my wishlist and I don't not want to give it away. This was just an honest mistake. I requested the book about a week ago when it showed up. I think I saw over 30 people wanted it!

So now I can't remove this book since it is on people's wishlist.

I just PM the person letting the know about the mistake. Once her request is canceled will I be able to remove it from here or will I have go through this with all the people who this on their wishlist?

As soon as someone accepts the request you can cancel it.  Don't ask them to cancel because they will lose their place in the wishlist line.

Yup, PM them to accept the offer so you can cancel it quickly and get them back in line for the book as quickly as possible (this usually gets them to act). If you are not hearing from the first WLer, you might want to put your shelf on hold again to catch it from going on to the next in line. Honest mistake. Easy to fix.

Either that or mark it 'I can mail it later' and then read it really quickly.

You can hold off on accepting the request as well for 5 days. Then choose the last possible mailng day which gives you 10 days to read the book.  But if you're worried about wanting to keep the book then just PM the person, explain what happened, ask them to accept and then cancel the request.  They'll stay #1 and you can repost the book when you're ready.  If it's coming close to timing out then put your account on hold just long enough to let the 1st request time out and delete the book.

I put my shelf on and off hold a lot.  I posted one recently thinking I'd read it quick.  Well I got busy and didn't have to read it-I was just going to wait a few days to accept the request and choose the last mail day-but when it looked like it was going to time out I went on hold. THen I just deleted the book before coming off hold again.

you can also contact TPTB and they can cancel out the transaction...