every time I perform Send/Receive sync with my webmail I download emails to keep them safe in my Outlook database. Recently I've reinstalled Outlook and now if I delete an email in my webmail it's also deleted from Outlook.
This is something unwanted since I sometimes clear my webmail because it runs out of space.
Is there an option to solve this?
Plus: Is there an option to recovery deleted email due from sync? (not manually deleted)
That is because your account has been configured as an IMAP account and not as a POP3 account. An IMAP account syncs the email folders whereas the a POP3 account can only download (a copy) of the messages of your Inbox folder of your webmail.
You can remove your IMAP account and reconfigure your account manually as a POP3 account via; File-> Account Settings-> Account Settings...
Emails that you deleted should end up in your Deleted Items folder (often called Trash for various IMAP/webmail implementations). As this folder syncs as well, it doesn't matter whether you deleted them in Outlook or via webmail.