Given that you've already taken some proactive steps by booting up in safe mode and generating backups of your files on an external hard drive, it's puzzling that you're unable to access the management tools to clear out the system data. It's possible that the large amount of system data could indeed be old Time Machine backups saved on the internal drive, but without access to the management tools, it's challenging to confirm or address this issue directly.
One approach you could try is using third-party disk cleaning software specifically designed for macOS. These tools can often identify and remove unnecessary system files, caches, and other data that may be taking up space on your internal drive. Popular options include CleanMyMac X, DaisyDisk, and Onyx. Be sure to download such software from reputable sources to avoid malware or other security risks.
If you're uncomfortable using third-party software or prefer a more hands-on approach, you could try manually deleting potentially large files or folders that you suspect may be contributing to the storage bloat. However, exercise caution when deleting system files, as removing critical files could potentially cause system instability or other issues.
If none of these approaches yield satisfactory results, it may be worth reaching out to Official Apple Support or visiting an Apple Store for further assistance. They can provide additional guidance or help you resolve the storage issue effectively.
