Human Resource (HR) manager can close the ongoing feedback cycle; 

from the Home screen Navigation Bar click on IKJoAUO--JNOgkQSPeg3AKbJBRvJ7cN6lw.png -> HR Administration


Click on Manage Feedback Cycle from the HR Administration Page, it takes you to the following page;


Click on Edit   OVAYDH_sxs17qWecmFkLRivePxEGZlpnVA.png  button/icon provided under the Action column against intended the cycle. It takes you to the screen given below.


Change the End date of the cycle in the Cycle Date option; make it to any date which is earlier than the Current Date.

Finally,  click on 1PDRqA71Xdx6prjjl0MRPcvmPpvO8CxYnA.png as the end of the page to proceed further. 

It is important to note that if the feedback cycle is closed, all pending action items related to the cycle can't be completed. You can also extend the feedback cycle by changing the end date.

PS: Synergita implementation for your Organization may vary from how the features are described here. The screen shots given here may also be different from what you see in your system. Please talk to the concerned person in the Organization for any specific queries.