One is not "dispensed of an obligation." Rather, "an obligation would be dispensed with." (i.e., - taken care of)
In the same way, one does not usually talk of "being waived of an obligation." Rather, "an obligation would be (itself) waived." (i.e., excused)
Likewise, one does not talk of "being exempted of an obligation." Rather, one would be "exempted from an obligation." (i.e., - freed from)
And that leaves just:
I know I am supposed to see you in person but, due to my medical condition, can I be spared of this obligation, please?Yes, one talks of being spared of (doing) something. This is the only one that works here. Not because it's less formal, but due to the collocation.
Were there any other possible choices other than dispensed, waived, exempted,.or spared?
Student or Learner