from the very tiny fragment you provide, it looks like you are
creating multiple circles, and each one is assigned to the variable
circle, one after the other. circle is not an array of circles, it is
just the last one. So circle.setMap(null) removes that last circle.
circle[i] doesn't work because circle is not an array. (circle is an
object of some sort, and when you try to access circle[i] it may be
pulling out a part of that object, which part does not have the method
setMap. Hence the error, maybe.)
You could try creating variable circle as an array, then in a loop
assign circle[i]= new google.maps.Circle(.....)
- Jeff