Issue tmpfs + devtmpfs clean

[cloude]

Plesk Obsidian v18.0.30 os_CentOS 7
CentOS Linux 7.8.2003 (Core)

My partition disk is full, but my website use only 6gb + 1.5gb for backup, it looks like the rest of the hard disk partition is dedicated to temporary files

how it’s possible to resize his space?

Thanks in advance for help.