Is it agents any rules to take a text set out of the custom folder from some one that has quit tb?

Ummm, Yes.

I think you have to have there permission still, Because if they come back...

Yup - unless you buy it or have permission from the owner it's a no no.

Aye thanks :3

I find it necessary to essentially repeat what skulfuk said, because I've seen quite a bit of this sort of thing recently and am not sure why people think it's okay.

You did not make the textures. Someone you do not know made them for someone else you do not know, with no intention of ever giving them to you. Just because they're no longer active on Toribash does not mean that their textures suddenly become public property. Usage of or attempting to sell textures of anyone without their permission, regardless of their state of activity, is seen as plagiarism and will be punished as such.