I am working in CFCL after doing Diploma in chemical engineering. Should I leave my job to pursue B.Tech/B.Sc?

Distance Education in B.Tech is not possible but you can pursue B.Sc. Easily through distance. You can also pursue Part Time or Evening Class B.Tech courses near your workplace. But since you have done Diploma in Chemical I would recommend getting admission in B.Sc. Chemistry. You can also get later

No, I don't think you should leave your job for B.Tech if you are looking for higher pay scale because with job you'll earn experience and experience will increase your salary but if looking for higher study then you can leave your job and pursue B.Tech and one more thing you should check Amie.