As a teacher, I would always let kids go. Although depending on the situation, I might say "wait a minute until -other student - comes back" or "just listen to this instruction first so you know what to do". You definitely get to know kids who ask to leave to get out of work, but rather than stopping them going, you need to work out why they are avoiding the work in the first place. Often it's anxiety about the work being too hard, or they just need a sensory break because classrooms can be overwhelming. In those cases, it's actually not that helpful to force them to stay in the situation anyway.
As a teacher, I would always let kids go. Although depending on the situation, I might say "wait a minute until -other student - comes back" or "just listen to this instruction first so you know what to do". You definitely get to know kids who ask to leave to get out of work, but rather than stopping them going, you need to work out why they are avoiding the work in the first place. Often it's anxiety about the work being too hard, or they just need a sensory break because classrooms can be overwhelming. In those cases, it's actually not that helpful to force them to stay in the situation anyway.