My father is disabled and I have guardianship of his property, can I transfer ownership over to myself?

If you have legal guardianship you are required to use your father's assets only for your father.  So, no you could not deed the property to yourself as a gift. Doing so would almost certainly be seen as a breach of your fiduciary obligations. 

If you are looking for ways to generate income to support your dad you could might consider selling the property at full market value or if he can stay in the home possibly doing a reverse mortgage.  I'd encourage you to make sure you have court approval before liquidating assets however. If an attorney handled your guardianship I suggest talking to that attorney about permissible uses of the property entrusted to you.  If you had no attorney you might want to consult one now.