All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
It is disliked to bury in a tomb that is built with baked bricks. However, if it has already occurred, the tomb must not be exhumed because the scholars explicitly stated that it is prohibited to exhume tombs.
Imaam An-Nawawi, may the Mercy of Allaah be upon him, said: “It is prohibited to exhume tombs for no legitimate excuse according to the agreement of the Shaafi‘i scholars”.
This is applicable if the tomb was built internally with baked bricks. However, if these bricks were outside the grave it is to be leveled to the ground based on the Hadeeth narrated on the authority of ‘Ali, may Allaah Be Pleased with him, that the Prophet, sallallaahu ‘alayhi wa sallam, said: “Spare no portrait unwiped out, and leave not a high grave unleveled." [Muslim].
Allaah Knows best.