- Do you mean the account at Settings > [name on top]?
To remove that, you would need to provide the Password for the account. If you forgot the Password, then you would have to use Account Recovery. If you do not know the account that is signed in there to reset the Password, then you would need to provide the original purchase receipt from Apple or Authorized Apple Seller to remove the Activation Lock.
- Do you see this account only when the App Store attempts to update some apps?
That means the app was downloaded using a different Apple Account. You would need to delete the app, then you can download the app using your Apple Account. Although that would not prevent you from resetting the iPad.
Not sure if you purchased the device used, from an unauthorized seller, or allowed someone else to enter their Apple Account on your iPad. No one can put their Apple Account on your iPad, unless they use your Password to remove your account. Knowing how that account is on your iPad in the first place, may help with providing any specifics or if a resolution is possible.