Hi Jayanthi,

when we have data in place we cant change data-type.you can do something like take a backup of the Data Object using Icommand.

and change the datatype in exported xml of Data Object.and import the same.

its like ricks if those Data Object are interlinked with any other data object or if you created reports on the same.

try something like this when you completed taking backup of all stuff

Regards

Shankar