Thanks for using Just Answer, in oreder to repair the e-brake you will have to replace the E-brake control.
I am sending you instructions in pdf format, hope this helps you out.
Click Here for Instructions
Do you have drum or disc brakes in the rear?
Since you are unable to relieve the tension, then you will have to remove the rear wheels and disconnect the cable at the rear brakes.
And for disc brakes
CLICK HERE FOR INSTRUCTIONS