The owner of the policy has all rights to the policy. In many cases the owner and the insured are the same person, but not in all cases. A parent may be the owner of a policy that they took out on a child when they were younger.
Owners generally have the ability to change beneficiary's, change death benefit provisions, and to cash surrender or take out loans against the policy.
If however a power of attorney were signed over by that owner then it is possible for the power of attorney to make changes to the policy as listed above.
Hope that answers your question.