You can apply but in order to apply for HELB loan, you need to have an admission letter. Therefore, if the institution you want to transfer from has not issued you with an admission letter, you will not be able to transfer.
However, be aware that HELB always deducts about Ksh 4,000 from every semester disbursement and sends it directly to a student's school fees account. Therefore, the money might go to the institution that you transferred from.