If you receive the following error when attempting to sell your tanks: Unable to sell 'X'. Please make sure that the vehicle is not in any tactical unit or try again later
This error is being caused by having an overfull barracks. In order to correct this error you will need to remove any excess crewmen until the number of crewment in your barracks is equal to or less than the number of available bunks.
Now that the crews have been reduced to be equal to the total number of bunks, the MKA we failed to sell earlier can be sold.
If these steps do not work to let you sell your tanks, please let us know by submitting a ticket to our Customer Support.