After removing an old shower you can either cap the cold feed off with a soldered cap end for permanent fix us as a temporary fix till a new shower is fitted you can use a push fit cap end or compression cap end.

However having what is called a dead leg ( a pipe, where the water stays in the pipe and is never refreshed with fresh water ) is a potential risk of legionella, taking it back to where it branches off the cold supply is how you should be doing it, ensuring the pipe you are removing is not supplying any other outlet.

Like one of the posts above try and remove the leg as close to the branch as possible. Avoiding dead legs , legionella etc . As per water regs standards !!

15毫米或22毫米soldiered cap is best solution if you are not going to connect another shower. I have never known a push fit to pop off, but I am a belt and braces man so soldier would be best!

If the shower was fitted correctly then there should be an isolation valve somewhere . Maybe under the bath or on the wall behind the shower .