Two Extensions on One Phone

[globaltwelve]

Back when our KX-TDA50 was installed, the installer piggybacked two extensions off of one phone jack (two people shared an office). The two people now have separate offices and one extension was moved (103) but the extension formerly known as 104 is now showing as 303. How can I undo what the original installer did and get 303 back to 104?

Any suggestions will be appreciated! I've combed the programming manual but can't find this situation.

 

[obtsystems]

In ext number prog 103 change ext 104 to unused number Eg 100 then change 303 to 104