بسم الله الرحمن الرحيم
(Fatwa: 547/496/M=5/1438)
It is better not to use high commode toilet as it generally carries the possibility of smearing impurity or impure splashes. If there is other toilet where you can sit on the ground in your office or nearby then use it and if you have to use high commode in compulsion then you should make it sure that the impurity does not get you. First clean the set clearly. If the floor may become wet in case you wash it with water then you may also clean the set with tissue paper. After your precaution and care, if yet the impurity gets you then wash it after leaving the place.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband