Once visa is cancelled you will have to leave the country before midnight of the day in which you go cancel your visa BUT you can ask your school/university to issue an official letter to show at the immigration stating that your visa -precisely your student status with that institution- will cease its validity on 20th. This will give you 4 days time (supposing you’ll go to IO on 16th) until 23:59 of the 20th to leave the country. Mods can tell you better, but I went through the same thing and that’s what I did.

@Ellie ******

sorry the dumb question… what’s the purpose of keeping both options for the same amount of days, but the e-visa has actually a cost? No one will apply for the 60 days tourist visa anymore?