Just got the task to disable the associated grid sorting in Dynamics CRM 2013
So i looked at the OOB CRM features to achieve this but found there is no option available to disable/enable the grid sorting :(
Then i extracted an unmanaged solution which includes the required entity and modified the "customizations.xml" as shown below.
After updating XML save it and import that back to CRM and you will notice now sorting is disabled for the particular column.
and if you want to enable sorting again then you will need to update disableSorting="0" or remove the attribute by following the same procedure.