Hey there, mootoosamy cunoosamy
If you are just wanting a OneDrive storage plan for your account, you can purchase these individually without a Microsoft 365 subscription. To purchase a OneDrive storage plan, please sign into your Microsoft account onto the manage storage page on OneDrive here: https://onedrive.live.com/?v=managestorage&sw=bypassConfig
Once you have signed into your Microsoft account, please click onto "Get more storage" to view the available storage plans in your region.

You can then choose from the available storage plans and follow the instructions to purchase a plan that suits you.
If you no longer want Microsoft 365, you can cancel this or turn off recurring billing. To do this, please sign into your Microsoft account on the Microsoft 365 subscription management page here: https://account.microsoft.com/services/microsoft365/details#billing
Once you have signed into your account, please either click onto "Turn off recurring billing" or "Cancel subscription"

Please be aware that if you do cancel the subscription, depending on your region and if you meet the requirements, you may be offered a refund for the remaining time left on the subscription. There will be a prompt on your screen when you cancel the subscription that will inform you of this.
Hope this information helps,
Nathan