I am sure he has been warned verbally earlier for late coming.
Where is the question of misbehaviour with senior-it appears to be a late coming problem which many people of this nature of job have.
Specifically mention late coming on frequent basis inspite of many verbal cautions in the warning letter.
You can issue a show cause notice detailing his frequent late arrivals and your attempts to correct him.
Give him 48 hours for response and then give warning letter.Keep one copy of his receipt/acknowledgement on file.
Ensure letter is legally worded in simple language and direct to point and in Marathi(local language)
""Apart from writing that you are appointed as office boy wef----
You have been observed coming late to office on-------,whereas your office timings are -----.
You are hereby to give explanation for the lapse by-----(48 hours date).In case no reply is received by----(date)suitable action will be initiated against you.
Signed by appropriate HR authority with date.
11th June 2016 From India, Pune