how to close all open chrome instance by keyword test cases

See https://support.smartbear.com/testcomplete/docs/app-testing/web/general/common-tasks/closing-browsers.html section To close multiple browsers. It has the exact Keyword operations required.

You get better control and speed and I highly recommend that you use code as per this article example rather than using KeywordTest, Close Action (Process and Browser Objects) | TestComplete Documentation (smartbear.com)

For KeywordTest implementation, you could use these Operations > Test Actions
"If Object"
"Process Action"