If you have forgotten your master password there is no way to recover it. So in this case, you can reset your Enpass to use it again. To reset follow the given steps:
NOTE: While resetting Enpass, all your data will be erased and we can't get it back.
If you have ever synced your keychain with any supported cloud, you need to delete the file from the cloud too, so that on sync your older data is not present there.
If you haven't sync then skip this step and move to Step III: