Create a string with date notation as dd-mm-yy or dd-mm-yyyy and delimitor as - or /.
Then use as.Date.character function to convert it into Date type.
date1 = as.Date.character(date,"%d/%m/%Y")
date3 = as.Date.character(date,"%d-%m-%Y")
date2 = as.Date.character(date,"%Y/%m/%d")