The process is simple as the picture you can see above.
Step 1: Open your desire Lead from the Lead Module
Step 2: You can see the button “Convert to Vendor” in the right top corner.
Step 3: Click the button, the Lead will convert to contact and vendor with no time.
The new contact will create with the Lead Name and the Vendor will create with the Company name.
Converted Vendor (the Vendor has been created with the Company name)
Note: The Lead will be delete during the conversion process, if you convert any Lead by mistake you revert it back from the recycling bin of CRM.