Is it ok to remove an old connection socket and cut the wire at the outside junction box for an old unused 2nd line. I want to remove the wire which goes round the house to the back room before I redecorate.
Yeah, it’s your house and if it’s not being used then go for it.
As long as you are 100% certain that line 1 does not go in that cable. Expect a large bill from your Comms Provider if you cut the cable if it does.