Multiplicity Steam activation failed after windows reinstall

Hello, I had to reinstall multiplicity from steam after reinstalling windows. 

When running on the new install, I got the error "Unable to active Multiplicity, as it's currently activated on a different computer. Click continue to deactivate the other computer and proceed with activation on this computer" 

However, it does nothing when selecting continue and just loops back to the same message. 

I need the old instance to be removed. 

Thank you.