I got a bunch of Hardback books that I would like to post but I do not want them a part of the BOB how can I go about doing this?

I haven't used BOB in a while, but whatever if on your bookshelf will be available for BOB. No way around it.

You can always decline the trade if the other person does not have hardcovers that you want.

Yep, just don't accept them as part of any trade. There's not any other way to really do it though.

Another alternative would be to turn off your BOB feature for awhile.

But, when you stop and think about it, are there no paperbacks that you want enough to trade that hardcover for? In the long scheme of trading your books, you will even out in the end and it won't matter whether you traded PBs in or HCs in and what you traded out. Unless you are specifically going to ONLY order HCs then it really won't matter. Most people consider a book a book when it comes to mailing. Lots of hardcovers weight less than 2 lbs. and if so that hardcover will only cost you and extra .34 cents to mail. If it happens to weigh between 2 & 3 lbs, it will cost you an extra .68 cents. Someones surely going to mail you something good in return. 

And I have a LOT of paperbacks that weigh WAY more than most of the HCs I've received! Decide how much you want the books you are looking for, compared with the .34-.68 extra cents to get them with some of those HCs that someone else wants more than you!?! Interesting food for thought, yes?

I agree sherry.  to get a book I really want I would gladly trade a hardback that I don't want.   finding want I want here on pbs is sooo convenient that it is well worth the extra in postage if I have to trade a heavier one for it.  I figue it evens out for the time and gas money spent that would have been running around trying to find a book that I want. 

You could always put a note in your profile or signature saying you don't want to include your HC's as part of any BOB trades if you feel that strongly about it.  That doesn't guarantee that the person doing the BOB trade with you will see either of the notes (if they just search for a book and click on your name when the results come up, they wouldn't see your signature or profile...just your shelf) but it would be seen by some of them.

Turn your Bob off, list your hardcovers and see how it goes.  If you get rid of them quickly, problem solved.  If they're just sitting on your shelf you may want to reconsider and let them be included (keep in mind I don't bob, so take my opinion with a grain of salt)