Unwanted Assets

Can someone please help, Iv'e been sent lots of free assets on the Bitshares platform, sounds great but its not.
Iv'e had sent to me many coins that are not worth anything, someone would send me 0.00001 of their asset and If I try and get rid of them it always costs more in fees than the value of the sale, and knowing how cheap Bitshares fees are that says a lot.
I know you can select ''hide asset'' but if I run a cookie clean or so on THEY COME BACK :S
Would Bitshares be able to have a free burn option or would that be impossible with how the blockchain works?
The main reason I wand them gone completely is because I feel that it slows down my account having loads of these assets in my portfolio, Thanks