Usually, no. On Canon EOS cameras, menu languages are generally built into the camera’s firmware, so there is no normal in-camera option to delete unused languages.

In practice, removing languages would require modifying or replacing firmware, which is not a simple or officially supported task. While some third-party or hacking approaches have been mentioned by users, these are outside standard Canon functionality and may carry risk.

If your goal is just to avoid accidental language changes, the simplest answer is to leave the camera as-is: the language setting is normally configured once and rarely needs to be touched again. If someone changes it by mistake, the menu location is typically consistent enough to switch it back even if you can’t read the displayed language.

So for a typical user, the answer is effectively: you can’t safely do this yourself through normal camera options.