It's rude to delete people's numbers.
Jane likes to clear out clutter on her phone from time to time.
Jane wants to get rid of stuff on her phone.
Jane isn't sure if the numbers are important, so she keeps them just in case.
Jane deletes a bunch of phone numbers that she doesn't recognize.
She gets an important call from one of the numbers and Jane answers the call.
Some of her friends cannot call Jane since their number no longer shows up in her phone.