Once I index my data, I would like to delete the original one. If for any reason I need the original one, I would like to know it is possible to recover it ? Maybe it is possible using the rawdata file.
If I understand the question correctly you are asking if it is possible to recover things like deleted logs or output that you have piped into Splunk?
It may be possible to use data recovery tools to recover the data from the machines if it hasn't actually been overwritten yet or zeroed out by a proper deletion tool.
Otherwise you could always just generate reports from Splunk that resemble the original, but may not exactly match the original.
For data recovery questions you're best off on somewhere like Super User