You don't need to.
If you are moving to another provider then just make sure that membership auto renewal is switched off and you port your number if you want to keep it.
Then you won't be charged anything more.
Then after several months (about a year I think) your account gets deleted from the 48 system.
See here:
https://48.ie/legal/terms-and-conditions#7
If you really want it deleted sooner than that then you'll have to contact 48 support and ask them how to do this.
See the link in my signature below.
Hope this helps.
