A easy acces to nanital is a over night bus journey from Delhi.You can easily get the tickets for destination and it cost u around 600 to 900 INR for per person.You can choose your pick up point from your near by place.
best option is take an overnight train reach to kathgodam first then get a bus to nainital from kathgodam. the best train is ranikhet express it start from delhi timing is around 10.30 & will reach by 5.30 am early morning to kathgodam. fare is around 220 to 250 sleeper class. from kathgodam to nainital bus fare would be around 50 rupees. you will reach nainital around 7 am in the morning. this can be the best & affordable plan to reach nanital. I use to do the same when I go to nanital. I hope it will help 🙏
You could take a train from Delhi to Kathgodam. Shatabdhi express. Then on hire a cab and head towards Nainital. Another express is Ranikhet express which starts from old Delhi. Coming to bus mode of transport, it takes 7 hours to reach Nainital from Delhi. There are daily bus services available. You can check with Red bus, Yatra and Goibibo. Kindly check once more regarding travel restrictions before planning and booking.
If you are travelling from Delhi with a group of people more than 3 in number, then own conveyance would be suggested to lower down the cost. If not, then there are buses from Delhi as well. Advance book the hotel from portals like MMT or Goibibo to avoid hassle free and economic stay. Full day & half day taxis for sightseeing are available in Nainital. You can find many hotels & dhabas at Nanital mall road for meals