If I have 50 GB icloud storage on my iphone can I use that also with my icloud account on my computer

Yes. iCloud storage plans are linked to the Apple ID that you use for iCloud, not to a specific device.

Sorry, I'm not sure what you mean by "full in my icloud account" and "not full in my icloud storage on my iphone" -- but if your iCloud storage is full, that would be an explanation for why it may not be syncing to all of your devices.

Alialfarhan wrote:

I can't cancel the 50 GB subscription

See the "Downgrade options" at the bottom of your screenshot.

Cancel upgraded iCloud storage by downgrading to the free 5GB plan. See instructions in: Downgrade or cancel your iCloud+ plan - Apple Support

I can't cancel the 50 GB subscription