The university does not want me to include my advisor's name on my PhD dissertation My advisor is leaving academia and I will graduating and writing a dissertation on the work that I have done in his lab under his supervision. I have no problem to include him on my dissertation but the university is not allowing me to do that.  

Will it be misconduct if I did not list him as a contributor in my dissertation?
If your university requires you to list a different person as thesis advisor, then that's what you need to do---rightly or wrongly, your university determines its policy there, and you need to follow it.

You, however, can certainly make the contributions of your former advisor clear in the acknowledgements.  As with many ethical questions, this can be safely navigated by the application of sunshine: if you clearly state your former advisor's contributions in the acknowledgements, along with the reason that they are not listed as your advisor, then you should not have any trouble with people thinking that you unfairly chose to exclude them.

Note also, that if you later make any peer-reviewed publications out of this work, then if it would be appropriate to list your advisor as a co-author, you can and should do that.