Hi @ambikaTewari_ATCI
I think that is essentially what the fender cookie is for, deriving the same ECID from the demdex cookie, using your AdobeOrgID. The third party cookie was introduced to solve exactly this issue. If you own domainA.com and domainB.com, the cookie storing the user's ECID on domainA will not be readable on domainB and without the demdex call, sending this 3rd party cookie to Adobe and in return receiving the ECID, you would not be able to reidentify the user (unless you are using the appendVisitorIDsTo functionality to append the IDs to link clicks. This will not work for direct typeins of the domains URL though)
so yeah, it basically does what it was designed to. I have not come across a different way to reset it. Deleting the cookie will obviously also inflate your visitor count
Cheers from Switzerland!