The minimum for Witr (Prayer with an odd number of units) is one Rak`ah and it has no maximum limit. Therefore, there is no harm in performing one, three, five, seven, nine, eleven, thirteen Rak`ahs, or more as Witr. This is supported by the Sunnah of the Messenger of Allah (peace be upon him) through his words and deeds. The learned scholar
Ibn Al-Qayyim elaborated on Witr in his book "Zad Al-Ma`ad fy Hady Khayr Al-`Ibad", which we advise you to refer to for more information. (Part No. 7; Page No. 174) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.