From the NVIDIA website, I didn't find a clue regarding the PTX ISA version in which support for sm_10 is removed. From my experiments, I have an intution that it is PTX ISA 4.1 in which the support for sm_10 is removed. Or in other sense 4.0 is the latest PTX ISA version supporting sm_10. Is this correct?
Yes.
The last CUDA version to support sm_10 was CUDA 6.0.
CUDA 6.5 shipped with the PTX ISA 4.1 document, and information covering sm_10 instruction support was dropped from that document.
However CUDA 6.5 still supported sm_11, sm_12, and sm_13, and descriptions of supported instructions in those architectures is still included in the PTX ISA 4.1 document.