Hey Trickybeavis, you can manage your registered devices through our Optus Sport website here. You'll need to login first and then click on our name on top-right then select settings. From there, you should see a tab labelled "Devices". This is where you can remove registered devices. Keep in mind you can only make changes to your 4 registered devices once every 30 days.
Hey @hassanmohamed - have you tried Casey's steps above? If you have any troubles, please raise a fault via the Optus Sport app's Help & Support so we can assist further.