Removes @group from the list of groups to which the bookmark
for @uri belongs to.
In the event the URI cannot be found, %FALSE is returned and
@error is set to #G_BOOKMARK_FILE_ERROR_URI_NOT_FOUND.
In the event no group was defined, %FALSE is returned and
@error is set to #G_BOOKMARK_FILE_ERROR_INVALID_VALUE.
Removes @group from the list of groups to which the bookmark for @uri belongs to.
In the event the URI cannot be found, %FALSE is returned and @error is set to #G_BOOKMARK_FILE_ERROR_URI_NOT_FOUND. In the event no group was defined, %FALSE is returned and @error is set to #G_BOOKMARK_FILE_ERROR_INVALID_VALUE.