The seat belt retractor, the one that the belt winds up into, has to be rotated backwards to release the tension. But because is attached to the floor you must unbolt it in order to do so. The shop manual recommends replacing the belt retractor after any collision. This is obviously a saftey precaution and a wise one at that.
From the manual; All safety belt assemblies including retractors, buckles, front seat belt buckle support assemblies (if equipped), shoulder belt height adjusters (if equipped), child safety seat tether attachments (if equipped), and attaching hardware should be inspected after any collision. All belt assemblies should be replaced unless a qualified technician finds the assemblies show no damage and operate properly. Belt assemblies not in use during a collision should also be inspected and replaced if either damage or improper operation is noted.