We assume that you want to use both modes, with RemoteApp mode as the default.
To do this, you must modify the following lines in the index.html file located in the C:\Program Files (x86)\TSplusClients\www directory:

<span id="accesstypeuserpanel"> <label id="label_accesstypeuserchoice_html5" for="accesstypeuserchoice_html5"><input type="radio" value="html5" name="accesstypeuserchoice" id="accesstypeuserchoice_html5" onchange="remoteAppPluginPopinHide();"> HTML5</label> ... 

<label id="label_accesstypeuserchoice_remoteapp2" for="accesstypeuserchoice_remoteapp2"><input type="radio" value="remoteapp2" name="accesstypeuserchoice" id="accesstypeuserchoice_remoteapp2" onchange="remoteAppPluginPopinShow();" checked="checked"> RemoteApp</label> </span>

You have to remove the checked attribute from the first label tag and add it to the last label tag.
Be careful though, any modification of the connection page from the AdminTool may erase these modifications.