Now i am deploying from Dev to QA server. 

Although the deploying has finished to QA but the   "Generating mobile apps" hasn't finished.

the status has been continuing more than 3 hours.

i checked the latest version in QA  and it definitely completed deployment.

How can i  cancel or complete this ?

I solved this by doing  the below.

  1. Write down the Staging ID of the staging that wasn't successfully completed;
  2. How to get the Staging ID? Go to Lifetime > Applications > Click in target environment name > Change Log > Check for "Created deployment plan #<NUMBER> between environments 'X' and 'Y').
  3. Access to https://<yourinfrastructure>/lifetime/ForceStagingClose.aspx and introduce the Staging ID that you want to abort.

Hi!

This tip of accessing https://<yourinfrastructure>/lifetime/ForceStagingClose.aspx to force the termination of a deployment was very helpful!

Just one note: You will need permission to be able to do this.

What this will do is terminate your deployment plan by marking it complete, but the execution will remain in whichever steps it was when it was terminated.

--Tiago Bernardo