If you need to change your Vimeo plan, you need to do so via the same method which you used to purchase it.
If you upgraded via an in-app purchase, the subscription is managed by either iTunes (iOS) or Google Play, depending on the type of device you are using. Instructions for managing your subscriptions are provided by each, linked below:
Deleting your Vimeo account will not cancel your Vimeo subscription with Apple or Google. This must be done in the appropriate store.
If you purchased your Vimeo plan via Vimeo.com or Mevo.com, you will need to manage your subscription via your Vimeo account as detailed here.