IN this article all is explained very well. As you are running dark site you can try (for example) to download the script from you pc and the put it on the cvm.

https://portal.nutanix.com/page/documents/kbs/details?targetId=kA0600000008dpDCAQ

If this not solves the issues contact support and they will fix it for sure. 

hello Jeroen, 

Thanks for your valuable response tried the below command however due to no internet getting a below error.

2023-08-23 09:53:21--  http://download.nutanix.com/kbattachments/1540/KB-1540_                                                                     clean_v10.sh
Resolving download.nutanix.com (download.nutanix.com)... failed: Name or service                                                                      not known.
wget: unable to resolve host address ‘download.nutanix.com’

Hence, I had to move forward to delete the Prism API logs old data of 2022 by which I was able to clear 5 gb.

Thanks again, the issue is fixed now.