Is it obligatory not to shave anal hair, or to shave it despite feeling discomfort, or only to trim it, after it has become coarser and caused discomfort when sitting or walking?

Shaving the aforementioned hair is recommended, not obligatory. If shaving it causes harm, there is no impediment to leaving it, provided one is careful when performing istinja (definition)' (washing after defecation or urination) so that no impurity remains clinging to the hair. If the difficulty is not extreme, then shaving is preferable because it is recommended and aids in the purification of the area. Removal by means other than shaving is sufficient to achieve the recommendation.