Hi @saikatdas0790,
as you can see here for Dragginz this was done via an NNS proposal that approved and SNS-upgrade just relevant for Dragginz.
Since it seem that there were no problems doing this for Dragginz and since multiple other SNS teams requested this, we propose to add this as an SNS feature - so that in the future every SNS can change the symbol by proposal.
This is on our roadmap, but due to other ongoing work, this will likely not be done in the next few weeks.