Pithoragarh is directly connected to Delhi with overnight buses from Anand Vihar ISBT (NOT Kashmere Gate ISBT). The nearest train stations to Pithoragarh are Haldwani-Kathgodam (Ranikhet Express from Delhi) and Tanakpur (No direct trains from Delhi). From Kathgodam you can get buses or shared cars via Almora to Pithoragarh (200 KMs) and from Tanakpur via Champawat to Pithoragarh (150 KMs).
The 95 KM long Pithoragarh-Dharchula route is an ancient route connecting Kumaon to Nepal and Tibet. Dharchula borders Nepal and is one of the many border crossings in the region on the banks of rivers Kali. But before that, you come accross Jauljibi, 65 Kms from Pithoragarh while Askote is a major village en route.