What is the best way to move local disk to cloud? retiring local disk storage

Create an AUX Copy to Cloud, select all the backups to be copied. Once that is complete, promote Aux to Primary.

https://documentation.commvault.com/11.38/expert/promoting_synchronous_copy_to_primary_copy.html

My preference is to create new Storage Policy Copies (pointing at your cloud storage), perform an Auxiliary Copy to synchronize the Primary and Secondary copies, then promote the newly created copy to the Primary Copy.

Edit: Dude beat me to it.

When i try to run aux copy, it just says no data needs to be copied. i’m using command center btw if that makes any difference. i have no access to commcell console

That is expected most likely because you created a Selective Copy. When you create the copy, go to properties of the copy and "Copy Policy" select what you need from Primary. Once that is adjusted, right click the copy again and view jobs. You should see jobs "To be copied" 

Make sure you also select the proper settings under selective tab. 

Keep in mind that depending on the size/number of jobs, copying to Cloud may take a long time and the more copies the longer it will take. Also I am assuming you have not stopped to run jobs on this copy, which means that as new jobs came in to the local disk storage, those will also have to be copied to Cloud translating in more time to conclude this task.