I am not sure what those weird charadtersare that you show in your image of the Manipulate
. They don't appear when I execute it, nor when I display it in the CDFPlayer (as opposed to Mathematica). What operating system are you on? I am on OSX. If they are appearing in a different OS then this should be reported as a bug to Homer Simpson...
But back to your original question... You can also use the AppearanceElements within the individual local variables of the Manipulate like this, for example:
Manipulate[u, {u, 0, 1, AppearanceElements -> None}, AppearanceElements -> None]
Or, in this case, to only get the InputField,
Manipulate[u, {u, 0, 1, AppearanceElements -> {"InputField"}}, AppearanceElements -> None]
Et, voila!