Need an advice about adoptables

[silv3x.livejournal.com]

Hello, AB! I need an advice about some adoptables I bought from another artists. Recently, I noticed I have some interesting character designs I don't use and I don't plan to use ever, so, I decided to sell them. Honestly, I purchased them because I wanted to support the artists and to have character designs by them. These ones (adoptables) aren't just plain one side pictures, they are good reference sheets. I have a problem with one of them. I wanted to contact an artist about reselling this adoptable, but they deleted their FA page, and I don't even remember their email address (so I don't know how much I paid for this reference). What should I do? Is it OK to resell it without artist knowing, or is it absolute no-no?

I also don't remember any friends of this artist, but I know some people who drew commissions for them. But it's kinda creepy to contact them about their commissioner.

The artist nickname was Nonus, hope it's OK to mention it.