As an example, this article shows how to disable activity log entries for the Attach Service Type Event from appearing in the Incident Activity Log List for all users.

Important Note: This solution is NOT supported by CA Technical Support as it involved changing the source code via WSP rather than using the WSP GUI to achieve the requirement.
Here are the steps to perform:
1. Using Web Screen Painter (WSP), open the "analyst" version of "detail_in.htmpl".
2. Click on the "Source" tab of "detail_in.htmpl" and find the following block of code:
<PDM_IF "$prop.view_internal" == "0">
<PDM_MACRO name=tab title="Activities" height=300 id=alg src="OP=SEARCH+FACTORY=alg+QBE.EQ.call_req_id=$args.persistent_id+QBE.EQ.internal=0">
<PDM_ELSE>
<PDM_MACRO name=tab title="Activities" height=300 id=alg src="OP=SEARCH+FACTORY=alg+QBE.EQ.call_req_id=$args.persistent_id">
</PDM_IF>
3. Replace the block of code in step#2 with the following block of code:
<PDM_IF "$prop.view_internal" == "0">
<PDM_MACRO name=tab title="Activities" height=300 id=alg src="OP=SEARCH+FACTORY=alg+QBE.EQ.call_req_id=$args.persistent_id+QBE.EQ.internal=0+QBE.NE.type=SLASTART">
<PDM_ELSE>
<PDM_MACRO name=tab title="Activities" height=300 id=alg src="OP=SEARCH+FACTORY=alg+QBE.EQ.call_req_id=$args.persistent_id+QBE.NE.type=SLASTART">
</PDM_IF>
3. In WSP, Save and Publish the change to "detail_in.htmpl".
4. In the web browser, clear the cache (in particular, the forms that are loaded).
5. From a command line prompt, run the following CA SDM command:
pdm_webcache -H
Here is the result of the customization, seen via the Notepad++ tool:

Here are the results:
