How do i delete my sons info from my i cloud account

Question

how do i delete my sons info from my icloud account

Answer 1

There's no way to automate this process, it has to be done manually.  And you'll have to first migrate a copy of the data to a different iCloud account on his device before deleting any data.  If you delete it before doing so, it will delete the data from iCloud and from his device and it will be permanently lost.
To do this, on his device go to Settings>iCloud and turn all data that is syncing with iCloud (contacts, calendars, etc.) to Off.  When prompted choose to keep the data on the iPhone.  After everything is turned off, scroll to the bottom and tap Delete Account.  (This will only delete the account from this phone, not from iCloud.  Your phone will not be effected by this.)  Next, set up a new iCloud account on this phone using a different Apple ID and turn iCloud data syncing for contacts, etc. back to On.  When prompted, choose Merge.  This will upload the data to this new account.  At this point you will have two different iCloud accounts, one for each phone, with identical data on them.
You will then have to go to icloud.com on your computer and sign into each iCloud account separately and manually delete his data  from your account, and vice versa.  These changes will be reflected on each phone.  When finished you will have individual iCloud accounts with just your own data on them.