I applied so much oil stain in a piece of wood of pine, and now it looks a bit weird (ugly).
I made a try with much less oil in an other piece of the wood, and looks better, so I wonder if there is a method I can use to remove the over used oil on the other pieces.
If the oil stain is still quite fresh you can usually wipe away some portion of the excess using paper towels or rags wet with plenty of mineral spirits/white spirit/turpentine substitute. But because the stain is intended to penetrate wood this might not remove enough to look the way you want, but there's no harm in trying it as it doesn't interfere with the next option.
If the stain has had a chance to dry well however (several hours to overnight or longer) wiping with solvent is unlikely to work well* so your only real option is to get back to bare wood by planing, scraping or sanding the surface off and then staining more lightly.
*And paint stripper tends not to do any better.
