So there is no way to turn off the reminder without spending more money or deleting files?

What reminder?

If you mean your iPhone Store is getting low, then no, buying more storage will not fix this.

If you man your iCloud Storage is getting low, then yes, you need to delete content from iCloud or buy more iCloud storage.

You need to explain exactly what you are talking about, before anyone can even begin to try to help you.

What reminder? Without more information, we can’t help you.

No idea what you’re talking about.