I can't access folder from a deleted iMac user to clear up space

Hi,

I deleted a username from my iMac following this steps: Delete a user or group on Mac - Apple Support

but I never got the option to delete the user's folder and now I have over 340gb on my computer's "System Data" that I can't access to delete.

The user's folder doesn't appear as (deleted) so I can't even restore the user to delete it from there, and all the folders inside are blocked, thus marking as zero bytes and I can't access them.

I don't know what to do to delete all this space. Thanks in advance.