Hello Watachi Kun
Thanks for your question.
Don't delete MFA app. The process of resetting your phone involves having to backup your credentials in authenticator https://learn.microsoft.com/en-us/xandr/curate/troubleshooting-multi-factor-authentication-mfa?source=recommendations
Deleting the MFA app requires you having to contact the admins of the accounts in question for work or school accounts.
You will need to contact the support teams of those applications to assist you in resetting your credentials.
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Regards,
Abiola