Firstly: it is impossible to delete your wallet. Once it is created, it will exist on the blockchain forever. See here.
However, it is possible to delete the MetaMask extension in your browser, or remove the mobile app. If you do this, you'll need to redownload it, and then follow one of these two options:
- Restore your wallet using the Secret Recovery Phrase
- In case you didn't save the Seed Phrase / Secret Recovery Phrase you can try verifying it with the vault decryptor
Please note you can only check the vault if you are on the same computer. Make sure to always keep your Secret Recovery Phrase safe.
To better communicate the importance of never sharing your seed phrase, we've changed the name of the phrase to "secret recovery phrase". Learn more here.