Resizing Vultr File System volume allows you to scale your storage needs depending on your current data usage. For example, you can scale up the storage size from 80GB to 160GB or down to 40GB. You can only shrink a Vultr File System volume to the current storage size. That is, if the current files have occupied 5GB you can't shrink the volume to a lesser storage like 4GB.
Follow this guide to resize a Vultr File System volume using the Vultr Customer Portal.
Navigate to Products and select Cloud Storage. Then, Click File System.
Select the target Vultr File System volume.
Click the disk size under Usage.
Enter a new disk size, such as 160 GB and click Update.