It depends on how much space you need, but from the sound of it your best bet would probably to buy an external HD and transfer some of your stuff on to it.
The fuller your HD the harder your computer has to work
What is ransomware and how do I protect my PC from WannaCry?
What I learned from my mentor, Oscar-winning VFX supervisor Phil Tippett
Siri vs Google Assistant
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.