When gw sending response back to the client it is embedding the below in the headers not sure how could I remove it,since I've requirement to remove this while sending to the client.Pls advice
It doesn't make sense.
Usually only if the client sends the header Accept-Encoding: gzip, then the server may compress the response and return the content-encoding: gzip.
So, it's better to do it on client side.
Or, maybe removing the Accept-Encoding header on gateway before routing to downstream could work, too.
The header assertion can change/remove a header,
Manage Transport Properties/Headers Assertion - CA API Gateway - 9.3 - CA Technologies Documentation
NOTE that the content-encoding header indicates how the response body encoded, they need to be matched, you cannot just simply change/remove the header.