this what i found in info web about PE
Your Question:
Q: Do I need to engage a Qualified Person / Professional Engineer for hacking or demolition of walls? Why?
[Home Owners > HDB Renovation Guidelines > Renovation Works]
A: Yes, flat owners need to engage a Qualified Person (QP) for removal of non-load bearing reinforced concrete (RC) walls.
Such walls are constructed with reinforcements connected to structural elements (eg. columns, beams, slabs and load bearing RC walls). The QP is to supervise and ensure that proper demolition works are carried out such that the existing structural elements are not affected.