If any exe's in the NetSim gets deleted due to Trend Micro antivirus here are some steps to add NetSim exe's as an exception in Trend Micro Application without disabling the Antivirus protection
Step 1: Open Trend Micro Antivirus, Click on Settings as shown in the figure.
Step 2: Click on Exception Lists
Step 3: Click on Programs/Folders
Step 4: Click on +Add
Step 5: Click on Browse
Step 6: Add bin folder from NetSim Directory which looks like "C:\Program Files\NetSim\ Acad_v12_1\bin" (In lower versions of NetSim, "C:\Program Files\NetSim Academic\bin)
Step 7: Click on Open
Step 8: Click on OK
Step 9: Click Apply
Note: Trend Micro Antivirus may have has previously deleted the NetSim executables. We recommend you uninstall and re-install NetSim.
Additional References: How to Perform Silent Installation of NetSim?