Baha'u'llah admits that Muhammad is the seal of both prophets and messengers!

"Salutations be upon the Master of the World and the Teacher of the Nations (Muhammad) by whom came to an end Messengership and Prophethood and [salutations] be upon his progeny and companions." (Baha'u'llah, Ishraqat wa chand lauh digar, p. 293)

(اشراقات و چند لوح دیگر ص 293)"السّلام علی سيّد العالم و مربّی الامم الّذی به انتهت الرّسالة و النّبوّة و علی آله و اصحابه "

As you can see even Baha'u'llah admits that Prophet Muhammad is the seal of both prophets and messengers but you somehow claim to be a Baha'i but deny this.

Baha'u'llah knew there would be no prophets and messengers after prophet Muhammad so he devised a new plan. If he were to claim he was prophet or messenger everyone would oppose him, so he claimed that he was God Almighty Himself. This is pretty obvious in his writings where he explicitly makes this claim numerous times. For example when he was imprisoned he would claim:

"There is no God but me the lonely, the imprisoned."

(Bahā’u’llāh, Āthār-i Qalam-i A`lā (Canada: Mu’assisiyi Ma`ārif Bahā’ī, 1996), vol. 1, no. 39, p. 226)