It is a pretty difficult and possibly hazardous to remove liners as the chemicals involved can be volatile and toxic. Depends on what the liner is. If it's Kreem, I think acetone will dissolve it (along with any paint). Many tanks from the States were lined unnecessarily, because of fear of corrosion was whipped up.
If you also want a professional paint finish, you could send it to Menno as I think the brew they dip it in out there will dissolve it.