Use the ICIClientSettings interface SetEnableDiskQuota method to limit the amount of space a user can use in a home folder. Use the same method to turn off the limit. Refer to User Account General Settings for an illustration of how this and other ICIClientSettings can be accessed in the Administrator interface.
Signature:
HRESULT SetEnableDiskQuota([in] SFTPAdvBool val);
0 = Disable
1 = Enable
-2 = Inherit