You can join Diploma engineering courses only. You can join as a lateral for the 3 years diploma course. As you have finished your ITI as Trade Plumber, I believe you can opt for Diploma in Mechanical Engineering. Since you will join as a lateral, you will be joining directly in 2nd year of this course and will need to spend 2 years to complete this Diploma(instead of regular 3 years). Please note ITI students are not eligible to get admission to Bachelor Engineering course directly.
If you have aspirations to pursue Bachelor's degree after Diploma course, you can go ahead and join Mechanical Engineering degree course as a lateral again. You will have to spend 3 years(instead of regular 4 years) to complete this degree course. The bachelor's degree will open up more opportunities for you in public sector companies or other core companies. You can also appear in National level Engineering exams like Graduate Aptitude Test of Engineering(GATE) and other competitive exams.