There's a thread for this:
https://www.namepros.com/threads/discuss-brandbucket-rejects.886738/page-12
Email them, and request your current domains be removed.
30 Days
I'd advise you to do your Homework first. BrandBucket has an established network of buyers, and even though their marketplace is growing, the extra volume is attracting more and more buyers. I mean why search a marketplace of 7,000 domains when you can search through 26,000.
My thoughts.
BrandBucket - The established leader
Namerific - Offers non exclusivity so you can sell your domains elsewhere
BrandRoot - Poaching other marketplace clients to increase their marketplace. They lead in organic traffic, but their secret sauce is still unproven.
I give BrandBucket more scrutiny than anybody else because I'm invested most with them. They have more resources than others, and without feedback and change, another marketplace could take marketshare. I don't see this happening anytime soon, so I would caution you first before you decide to leave BrandBucket.
I will add that I'm always interested in what
@bazabizo is doing. He left BB recently, and is brokering his own domains, I imagine he's generating less leads, but the leads he does get, he has exclusivity to offer the enduser other domains he owns.