Once, i wrote a paper for Business communications. I think some essential paper in the second year may be.
There was one question which I got right and all my peers got wrong. I was quite happy for that, but now I realise, that the incorrect answer to that question, today is in common usage, and threatens to soon get into Indian dictionaries (or has it already?) as the correct grammatical usage.
Look up Webster's or Oxford dictionary for "dispose of", and you find:
Verb: dispose of
1. Deal with or settle
"He disposed of these cases quickly"
"The company wants to dispose of the equipment"
Dear users of English Language, "Dispose off" is just weird, incorrect usage of the words.
While "sell off" is more appropriate where the incorrect usage of the phrasal verb is happening, readers will appreciate, that the correct usage of "dispose of" is closer in meaning/reference to "to get rid of".
Again. Do not use double 'F'. 'Dispose Of' - Correct
'Dispose OFF' - Incorrect.