Mac Mini: reset password.... also need help with my emails

Good day,

i recently reset my password for my mac mini but as i never log off i have forgotten the password 😟 I am still logged in but i can't change the password without knowing the last one.... Is there a way around this?

Also....

I connected my email account to the mail system on the mac mini and it copied all of my emails over onto the hard drive... this i didn't want as i need to be able to use the emails while i am on the road... Is there a way that i can move them back? If not is there a way that i can pull them onto my icloud account or any other account from apple that i can have access to them....

This will also cause issues if i have to reset the mini i am worried i will loose all my emails.

Thanks for the help!