How can I stop the download of IOS.IPad,And Apple I Phone 3

Question

Have had  problem with storage, so requested to go to settings, and that said to download I O S, on my Apple I Pad Minnie , and my Apple  Version 3 Mobile, and now both are slow, especially my I phone, that is Stuck only on the Apple sign How do I I Fix this or stop this , or delete so have ph in use Solveig