I just had my PC Repaired & I cannot Log OUT of the New Owner Account

Can I get some help please baby-steps If u can Please
I just had my PC Repaired and I cannot Log out of the New Owner Account they created and all my stuff is in 7 other accounts? Nor can I Sign in to any other Account I am stuck in the New OWNER ADMIN Account and cannot change anything
⦁ Administrator - Original
⦁ Dasha
⦁ Dasha Administrator
⦁ Dasha Administrator S
⦁ Default
⦁ Defaultuser0
⦁ Owner (Administrator) NEW
And
When I open a Firefox Page New Tab Blank Page it opens 6 or more and the computer slows down to a crawl then I have to >Task Bar > Firefox 6>End Task?
I think that all the other Accounts may be opening their own Firefox Pages when I open one in Owner Admin?
Its to long and too ugly to try and explain it all to you it may be easier if I Run a Program that can show you the entire mess Or a Heap of Screen Shots
Thank you for any help you can offer Dasha

Thanks AddRAM' there is no option to Switch Accounts as in every time I try to Switch Accounts Pc reboots back to Owner Admin Account log in there is no other option of another account to choose from on the Lower Left on the restart page only the Owner Admin Account Log In, Dasha

Right click on the start icon. Log out will then be an option on the power icon submenu.

Does it show users in the users and are the users profiles on the pc in explorer it sounds as if they have done a clean install

Reply ’Firstly' NAVYLCDR' Re Your advise: "Right click on the start icon.Log out will then be an option on the power icon submenu"
It shows: Shutdown, Re-Start, Sign Out, Sleep and Re-Start BUT I cannot log onto any other Account coming back in? there are no other User Account Choices listed on the opening Page to Log onto? Nothing Just; OWNER Sign In D....l M.....L and Password' I tried Settings > User Accounts and there is only Owner Admin, none of the other Accounts are reachable? If I to try" sign in with a Local Account Instead a small blue popup has OWNER D...L M.....L and My Email address below and ask's me to add my NEW Password? I cannot even access my MS Account

Sumuria: Does it show users in the users and are the users profiles on the PC in explorer it sounds as if they have done a clean install
I thought that too But I am still baffled as to just what they did as I had the Users > User' Choice before and the all the other Accounts I listed had all the Different Apps in them but no Owner Account all of Drive C// Western Digital Ex HDD Terabyte has been loaded with Drive C they still have the Western Digital 1 Terabyte That happened when I tried to Record a Boot Drive 9 Months Ago Drive C is showing 926 GB
If I Go to > C// User I get: Screen Shot One 01 and if I open any of those "Accounts they only have Apps and Data in a few But if I > C// UserS > User -- then I get all the Data as it should be the UserS User Administrator Dasha Administrator and at least one other (Owner) Standard Account would be the Usual. It seems that the Users USER account is the Main Acc but I cannot get into it see: Screen Shot 02 Two Sorry Guys I Cannot get s