Ivy here from Shopify.
I am sorry to hear you are considering closing your store - can I ask why?
If your store is currently on the fully paused plan, then you will have to reach out to a Support Advisor in order to close your account. We have 24/7 access to support via our Support Portal here - you do not need to have an active store to have access to this support. If you simply input your query into the "ask about a topic" search bar, the option to contact live support will then appear.
Since this is the next step I've marked this reply as the solution for the benefit of others who may discover this topic. Thanks! Ivy