Getting rid of a SiteKiosk

I run a hotel in NJ. I recently got rid of 'Uniguest' which was our hotels sitekiosk. When we did that they would not give us the admin password making the computer useless. Whenever I turn the computer on it starts uniguest and a screen saying "please contact uniguest" comes up. I want to restore the computer for normal use with windows but without the admin password there is not much I can do. I have already tried to reset the computer using the command prompt but access gets denied because I am admin blocked. if there is any way to use this computer for normal use please help me out.
Thank You

 

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