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 GPEX Wallet 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
- If you don't have your Secret Recovery Phrase, you may be able to retrieve it using the vault decryptor
Please note you can only check the vault if you are on the same device. Make sure to always keep your Secret Recovery Phrase safe.