To delete cash app account you have to make sure that you have taken all money out from the account. Explore here to know more about Cash App .
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Before closing the account, tap the Cash Out button on the app's home screen to move funds out of your account.
Then, select your Profile icon and tap Support > Something Else > Account Settings > Close Account > Close my Cash App Account.
You can delete the app from your phone once your account is closed.