Question

how did the british ruler stopped the inhuman 'sati practice'.

Answer 1

Under British rule, the practice was initially tolerated. In the province of Bengal, sati was attended by a colonial government official, which states historian A.F. Salahuddin Ahmed, "not only seemed to accord an official sanction, but also increased its prestige value".[10] Between 1815 and 1818, the number of sati in Bengal province doubled from 378 to 839. Under sustained campaigning against sati by Christian missionaries such as William Carey and Brahmin Hindu reformers such as Ram Mohan Roy, the provincial government banned sati in 1829.[11][12][13] This was followed up by similar laws by the authorities in the princely states of India in the ensuing decades, with a general ban for the whole of India issued by Queen Victoria in 1861. In Nepal, sati was banned in 1920. The Indian Sati Prevention Act from 1988 further criminalised any type of aiding, abetting, and glorifying of sati.

Answer 2

Steps taken by British Ruler to stop inhuman "sati practice":

In mid nineteenth century, “British East India Company”, during the time spent stretching out its standard to the majority of India, at first tolerated all the followings of India.

William Carey, a Christian evangelist, noted 438 Sati victims inside a 30 mile (48 km) sweep of the capital Calcutta, in 1803, regardless of its boycott inside Calcutta. Between “1815 and 1818”, the quantity of “sati in Bengal” multiplied from “378 to 839”.  

Resistance to the act of sati by “Christian evangelists” Carey, and Hindu reformers like Ram Mohan Roy, eventually drove the “Governor-General of India Lord William Bentinck” to order the Bengal Sati Regulation, 1829, announced the act of burning of widow women along with prey of her husband as a criminal act.