Once you have your account structure setup in SAP BTP Cockpit, navigate to Global-account → Sub-account → Space. Afterwards click on SAP HANA Cloud from the menu on the left side of the screen.
For the candidate SAP HANA Cloud instance, navigate to Actions → Open in SAP HANA Cloud Central.
A new tab will be opened for SAP HANA Cloud Central Cockpit and your list of instances will be displayed for a selected space. From Actions column, click on the 3 dotted icon.
Select Edit from the menu.
From the new wizard, kindly navigate to Size section and click on + button for Memory or Storage as per the requirement.
Once changes are done, click on Save button and you are done. Note : At the moment, decreasing of resources is not available via self service, so kindly open a support message in HAN-CLS-HC category and they will take care of the task.