Change of user Id names in production server

Can we change User ID's Name in Production Server??

My User Id has been created with name Ramya Now we want to change to generic Name  For example: HR1 Can we do that in production server?

I told basis consultant to do that? But he said that User id is created with name Ramya we cannot change he also said we cannot delete and create as user id has got licensed and all

we just need to change user id How we do that >>>

Experts throw some light on this??