Welcome to YittBox. Thanks for posting this question. 
To minimize the navigation pane, but not hide it completely, you can try this code:
     DoCmd.NavigateTo "acNavigationCategoryObjectType": DoCmd.Minimize

If you want to hide navigation pane, use the following VBA:

DoCmd.NavigateTo "acNavigationCategoryObjectType"              'This selects the navigation pane - if already hidden, it will open it
DoCmd.RunCommand acCmdWindowHide              'This hides the navigation pane

Alternatively, you can also do the following VBA:

DoCmd.SelectObject acModule, , True               'This selects the navigation pane - if already hidden, it will open it
DoCmd.RunCommand acCmdWindowHide            'This hides the navigation pane

Please note, this will produce an error if you are using the Runtime version of Access (since the navigation pane is disabled). To work around this, you would have to check the SysCmd(acSysCmdRuntime); something like this:

If SysCmd(acSysCmdRuntime) = False Then
    DoCmd.SelectObject acModule, , True
    DoCmd.RunCommand acCmdWindowHide
End If