You can find a bunch of related text strings when searching for "browser" in the studio's text editor. The strings browser-support.alert.text and page.browser_unsupported.message look like relevant
The message should be triggered by unsupported browsers listed in Khoros' Supported browser information - Do you need it to show with different configurations?
What's motivating you to get this message to disappear? Visitors on unsupported browsers won't be able to use all your community functionality, so you would really want them to use a supported browser. Do you mind sharing which outdated browsers you see still being used in your userbase?
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