Hello saroj101,
When you deleted the app, did you offload the app? If so, this would delete the app but keep its documents and data. If you would like to remove all its content, when visiting the screen that is showing in the screenshot, tap on Mail and you should see the option "Delete App". This will remove the app along with its content.
You can also take a look at the following resource to manage your device storage: If you need more space for an update on your iPhone, iPad, or iPod touch
We hope this helps.
Thanks for using Apple Support Communities. Have a good one!