It is not possible to reduce the size of an existing filesystem. You can only
expand it.
Creating a Filesystem

Attaching Storage to a server
Connect filesystem to server
From the Latitude.sh dashboard, navigate to Bare metal and go to Storage. Click Connect to bare metal and copy the code shown.Log in through SSH to the server you want to attach the filesystem to and paste the code you just copied. When prompted, enter the directory where you want to mount the filesystem.

By default, only
root and storage-users can write to the filesystem. If
needed, you can give others write access by using sudo usermod -aG storage-users [username]