To set an Icewm property of a window, you need its class and/or instance, which you can find with Icesh:
icesh list
Then click the desired window. For an Xterm, you will find xterm.XTerm as the class.instance value* in the next-to-last field.
Then one would use that value in ~/.icewm/winoptions
to set a property; say, to display no title bar for Xterms:
xterm.XTerm.dTitleBar: 0
and restart Icewm.
Now, the task bar is a special window for which Icewm does not seem to honor a winoptions
setting anymore (although older versions did, see the revision history). Still, there are several options for it in the preferences
file, for example to set its layer to Below. If you absolutely want it to set it to Normal,
icesh setLayer Normal
or if you don't want to point-and-click,
icesh -w "$(xdotool search --class '^icewm$' search --name '^TaskBar$')" setLayer Normal
*xprop | grep CLASS
can also be used to retrieve that information.