The office memorandum directed personnel to minimise their consumption of office stationery by up to twenty percent.

While 'minimise' technically means to reduce to the smallest possible amount, in the context of being reduced 'by up to twenty percent', 'reduce' is the more accurate verb since minimising implies bringing to the lowest level, not a specific percentage cut. 'Reduce' means to make smaller or less in amount, degree, or size, which aligns with cutting consumption by a specified percentage. 'Supervise' means to oversee. 'Surmise' means to guess. 'Lower' is possible but less formal and precise than 'reduce' in this official memo context. Thus, 'reduce' is the best improvement.