Actually, I did not understand your question, what I got is you are asking that you have got the seat under PMSSS and you are doing some integrated course from outside then yes you can get admission under PMSSS and you can join the college which is allowed to you.
or you are asking that you want to cancel the seat which you have got through pmsss and want to apply again in PMSSS. Then you can apply only if you have not got the allowance from pmsss i.e you have not been benefitted till now through the PMSSS. There are some cases where students cancel admission after one semester and they have to refund all the amount got from PMSSS then in that case you can apply again next year. But if you have already studied through PMSSS for 3-4 semesters and have fully benefited through this scheme before then you cannot apply again.
Read another answer where the student canceled his admission last year and he was able to apply this year also.