I have added near one hundred Tor bridges line in configure file torrc, when the bridge is unuseful you may get a warning from ARM (a Tor relay manager), can I delete these kind of Tor bridges this time, or they will relive later or sooner?
I think that ARM is just telling you that the bridge isn't working. Many bridges are run by volunteers, and may go offline and then come back. However, bridges are only useful as long as censors don't know their IP addresses. So it's safer to use the freshest (newest) bridges that you can get, and to get them as privately as possible.
