Is this possible to change the local repository location in tower application ?
Tower does not offer a specific "relocate" feature. The reason behind this is that it is very easy to simply remove the repository (right-click on the repository then select Delete) and then re-add it by dragging and dropping it to the repository view from Finder.
In any case, adding a specific option for this is on our list of things to do, happy to add your vote to this feature request!