Here is the one line code, using Invoke code you can achieve it
array.ForEach(Directory.GetFiles(“YourFolderPath”).Where(Function(x) New FileInfo(x).LastWriteTime.Date < Today.Date.AddDays(-26)).ToArray,Sub(x) File.Delete(x))
If are would like to proceed with regular method…take the below code and paste it in the For each and then use Delete activity…
Directory.GetFiles(“YourFolderPath”).Where(Function(x) New FileInfo(x).LastWriteTime.Date < Today.Date.AddDays(-26))

