From your station you should be using #6051.

From the display it looks like call forwarding is set on an Phantom DN, possibly used as an alternate intercom key. If your phone lable has multiple keys marked as Intercom, then you should try entering entering #6051 from all of your intercom keys.

It is possible that there is some other reason that a Toshoba tech setup call forwarding from one phantom extension to another phantom extension. Since I have no way of knowing how this is being used, just know that removing this call forward may have unexpected results. It may also have been setup for a previous user to call forward when the user is on a call, to a secondary extension.

That being said, you could also try using remote CF cancel, #6052+ 51234+#.