I completed my HSC from science & have also done 1-year course of interior design and decoration from ITI, can I do a degree course?

Yes, you can do Degree Course in interiors. Institutes like Arch Academy and NID have Interiors and space Design Degree courses.

Of course, you can join degree course on the basis of your HSC Science also. Even your ITI one year course is also not required for the same. ITI course is additional advantage.