No, character level progression is permanent. Once leveled up, this action cannot be reversed.
Recommendation for New Players:
Always equip SoulChant(+9) when leveling to optimize your character build.
Alternative Solution:
https://shoppingmall.99.com/en/web/treasure.aspx?gametype=104_100
The Optional Rare Yellow Rune(B) Pack in Treasure Mall includes:
a. Soul Chant (required for optimal leveling)
b. Additional rare enhancement items
Price: $229.99 USD
Note: This pack provides progression tools, not level reversal.