My DELL Latitude E6410 is old but it was working before but now I cant get past the DELL logo…If I do, the windows logo...

iCloud is very difficult to disable but you dont need to really replace your motherboard. Did you forget your password, if you did you can connect it to a laptop which has iTunes and use that to reset your iCloud. Actually you can also try out third party software like dr.fone for iOS and it will help you delete your iCloud account from the phone. Warning: You will lose your data which is on your iPhone or iPad etc. But dont worry there is always a solution to every problem. After you finish deleting your iCloud account you can retrieve all your lost data by using third party software like iMyPhone recovery or dr.fone itself and many other iPhone recovery tools available on the internet. Please let me know if you need extra help.