function removeSearchAlias(alias, search_leader_key, only_this_site_key) {
        if (!isInUIFrame()) {
            front.removeSearchAlias(alias);
        }
        unmap((search_leader_key || 's') + alias);
        unmap('o' + alias);
        vunmap((search_leader_key || 's') + alias);
        unmap((search_leader_key || 's') + (only_this_site_key || 'o') + alias);
        vunmap((search_leader_key || 's') + (only_this_site_key || 'o') + alias);
        var capitalAlias = alias.toUpperCase();
        if (capitalAlias !== alias) {
            unmap((search_leader_key || 's') + capitalAlias);
            vunmap((search_leader_key || 's') + capitalAlias);
            unmap((search_leader_key || 's') + (only_this_site_key || 'o') + capitalAlias);
            vunmap((search_leader_key || 's') + (only_this_site_key || 'o') + capitalAlias);
        }
    }
Remove a search engine alias from Omnibar.

@param {string} alias the alias of the search engine to be removed.
@param {string} [search_leader_key=s] `<search_leader_key><alias>` in normal mode will search selected text with this search engine directly without opening the omnibar, for example `sd`.
@param {string} [only_this_site_key=o] `<search_leader_key><only_this_site_key><alias>` in normal mode will search selected text within current site with this search engine directly without opening the omnibar, for example `sod`.

@example
removeSearchAlias('d');