Hi, I'm Mr.med. Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP.
What is the name of your Tablet, It is Samsung tab 4? what type of accounts are you trying to delete please?
It is your gmail account ?
Go to "Apps" "Settings" > "Accounts". Select (the account you want to delete, eg : Google) and click on delete.
Let me know the results please
Has everything worked out ?