Great way to get the trees (& stumps) out if the machine is properly sized for the size of trees that need to be removed.
Enough of a size difference in favor of the machine, and it can push over the trees and remove the stumps on it's own, but otherwise the (potentially safer) option would be to cut down the larger trees and use the excavator to remove the stumps. In the case of the latter even a small mini excavator can dig out the stumps from some fairly large trees, though getting the stumps out of the hole could become a problem if the stump is beyond the lifting capacity of the excavator.