Putting to rest the myths about Task Killers/RAM Optimizers and the like
Clean Master will do a lot more harm to your phone's performance than good, and the company behind it are notorious data-thieves and spammers. Whatever else you do, delete that and any other Cheetah Mobile apps.
And the "keeping restarting" is part of why these things are worse than useless. Android works on Linux principles for managing RAM, and will keep previously or frequently used apps dormant in memory to save power (empty RAM is wasted RAM). Killing them just wastes energy, since the phone will dump them itself if it needs the RAM and otherwise they will most likely be reloaded after you kill them, all you are doing is confusing the OS's process management. If you have a rogue app then identify it and get rid of it, otherwise you genuinely will be better off leaving stuff alone.
And you'd need root privileges to do what you are actually asking.