What do you mean by "my o2"?

I want to Port my O2 mobile number   to other service provider. Please let me know the process of portability.

Hello @Gayatri ,

is your contract still running or do you want to have the number ported over at the end of the contract? Generally you will have to initiate the process with your new provider. You might have to have the number be released first on our end. You can do that on your own through your mein o2 account.
While logged in to Mein o2 simply navigate to “Tarif & Optionen” > “Rufnummernmitnahme” > “Rufnummer jetzt freigeben”.

Schöne Grüße, Sven