There are several reasons as to why any high ranking official is difficult to remove. In the case of Nepalese politics, the Chief of Commission for the investigation of the abuse of authority is dealing with a culture that is filled with corruption. The CIAA website stipulates to this:
Corruption is a social evil having pervasive nature. It is prevalent in various forms and dimensions. It has been deeply rooted in society as a 'convention', 'tradition', 'psychological need' and 'necessity' with a regular practice not only in public service, but also in business transaction and other kinds of dealings as well. All strata of the society have been adversely affected by corruption.
The corrupt nature of the political scene in Nepal has made it difficult to remove anyone in the position of governmental authority. This extends to the Chief of Commission who is charge of overseeing elements concerning the abuse of power.
I think that another reason that helps to explain why it is so difficult to remove the head of the committee that investigates abuse of authority is because there is not an institutional framework in place to address such issues. The CIAA has been recently created. Accordingly, there is not a sufficient process in which members of the CIAA are recalled, admonished, and removed. The laws in Nepal indicate that the President appoints the Chief of Commission. In this instance, Ram Badan Yardav appointed Lokman Singh Karki as the Chief Commissioner of CIAA on May 8, 2013 for a term of six years. There is no institutional recall measure. Even though the Supreme Court of Nepal has argued that Karki should not be in the position he occupies given both his past and present, the reality is that there is no recall method established in the Nepalese institutional framework. As a result, it is really difficult to remove him from his post and this makes it very difficult for the CIAA to accomplish its end goal of "the rule of law" in Nepal.