If you talk about computers as whole and in-depth long term courses, mathematics is an important subject. For short term and specialised courses, it is not; e.g. designing, networking, internet technologies, etc.
Computers field is very vast and there are so many sub-areas and for each sub-area there are different types of courses for students. Better, if you take all required subjects including maths, otherwise number of opportunities will be lesser, especially in the field of computer science.
For engineering courses, Physics, Chemistry and Mathematics all are required at 10+2 level. For MCA, Mathematics is required(generally). However, for some other courses specially related to IT, computer applications, and administration; mathematics is not necessary. So, you can choose a course or field accordingly. Decide what career you want to consider and then do what is required.