For the admission to the course of BSc Psychology one need to complete the 10+2 examination with necessary subjects as instructed by the universities. Now on the basis of Diploma in Computer Engineering, you won't get a admission to the BSc course. If you want you can go for the lateral entry examination through which you can go for the BTech course and can get admission directly to the 2nd year of BTech. Most of the later entry examinations don't have any age limits. So you will be eligible for it.

To know more about BTech Lateral Entry visit the link below:

https://engineering.careers360.com/articles/what-btech-lateral-entry-eligibility#:~:text=Tech%20lateral%20entry%20is%20the,first%20two%20semesters)%20of%20B.

To know more about the BSc Psychology course visit the link below:

https://www.careers360.com/courses/bsc-in-psychology

I hope this answer helps. All the very best for your future endeavors!