What is the ruling of Islamic law regarding a husband's request to his wife that she not remove her hijab in front of her maternal uncle?

A woman's maternal uncles are her mahrams, and it is permissible for your wife to display her adornments in front of them. If you ask her not to remove her hijab in front of them, then if there is suspicion or a likelihood of fitna (temptation/strife), your action is not blameworthy and may even be obligatory. However, if suspicion and the likelihood of fitna are absent, you should not do that, because it creates alienation and causes the severing of kinship ties. The Sharia has forbidden everything that spoils relations between Muslims and severs kinship ties. Therefore, do not proceed with this matter, out of consideration for the rights of kinship and affinity.