If you use a character that you have leveled up to promote another character, you will recieve back all resources used to level it up.    

For example, if you used a level 21 character to promote a different character, you'll get back all of the resources you used to get that character to level 21, and the character will be removed from your Roster.

If that same character had equipment attached to it, that equipment will go back to your inventory.