Just in case anyone missed this.
Can this be done while the DISK is mounted over SHELL.
Because I dont have physical access to the SERVER.
And I assume from the information provided that sda3 is the / partition.
You would want to resize vs delete sda3 to create multiple partitions which can be accomplished using gparted. However, resizing requires the / partition to be unmounted which can not be done from a remote location.
To resize you will need physical access and boot the system using gparted's LiveCD and as stated be sure to back up anything important.