You mean when you reg a name that you think is worth millions only to find out it's crap & want to drop & get a refund? If so, you can do it for free @ Dyandot, Godaddy if you email them & Moniker with a 25cent "restocking" fee.
There is no reason that they'll be annoyed but even if they are it shouldn't lead to any problem from you. So just go with it.