you need to remove the association that Google Chrome has with the Tel command
On a Windows 8 machine there is a registry entry as below that needs to be deleted to stop calls trying to open in Google Chrome.
Use ‘Regedit’ to open the Windows Registry and go to :-
HKEY_LOCAL_MACHINE > SOFTWARE > Clients > StartMenuInternet > Google Chrome > Capabilities > URLAssociations
In there will be an entry called tel. Highlight this entry and delete it.