This is because my messages won't send on my new Huawei y6 2018. I'm trying to rectify this but how is the question. Cheers Kevin
You should be able to revoke that permission from that app by going into Settings app, into All apps or something similar that shows installed apps list, use a toggle if system apps are not shown by default (usually from a three dot line in the top section, towards right and below status bar on the screen). Click on the entry of your message app, go into Permissions option and toggle the permissions you want.
You can alternatively clear data of that app. Clearing data revokes all the permission ever enabled for an app. It however would also delete all your custom settings and preferences.
Furthermore, your phone may also have a feature to enable or disable permissions separately. You should browse the Settings app for it.