I'm going to delete my ex-partner's contact number and other information in my phone
Why are you deleting your ex-partner's information?
Because I don't want to see his pictures, read my memories and I don't want to re-play the past again.
It is good to cut ties with an ex.  It starts the new phase of your life in a fresh way.
Fuck you, it is not about starting a new phase. I'm going to do what I want with my phone.
Don't be angry, it is upsetting to end a relationship but you should try to control your emotions. It will be good for you to cut ties completely with your ex so you can start to heal.