Googleスプレッドシートで空白のみのセルを削除する ref: http://qiita.com/tanaike/items/1e93a0355aaef8355035

file0.txt

var ss = SpreadsheetApp.getActiveSheet();
var data = ss.getDataRange().getValues();
for (var i in data){
    for (var j in data[i]){
        if (data[i][j].length > 0 && !/^[a-zA-Z0-9]+$/.test(data[i][j])){
            data[i][j] = null;
        }
    }
}
ss.getRange("A1").offset(0,0, data.length, data[0].length).setValues(data);