VISA Refused and removal letter from HO

Dear Member,
my cousin have received the letter from HO saying that his visa has been refused due to not sending the Passport and now he has another letter for detained and he need to report to Police station, he has done is Master degree from University recently, he has asked HO to give him sometime so that he can sort out his issues here, what option he has now, he is planning to go back within 3 months time, will this be OK? or do he has to go back straightaway. but on the letter it mention that he need to report every month.
if he stay here i understand he will get banned for one year, or do he get banned for 5-10 year, he may be want to come back after some time,

your help would be highly appreciated

Regards

What kind of visa did he get refused?

What is his immigration history in the UK?

he was student here and he came about 3 year ago on university