Deleted

If someone checks your account, notices the missing wins and makes a ticket, you'll get suspended.

Some wins will probably be delivered more slowly because of people checking with support to see if you've gotten your suspension yet. And it is a bad look generally because deleting stuff someone was kind enough to give to you is rude.

You don't have that many won giveaways. You can try to reach out giveaway creators and ask them to delete that giveaway via support.

Stop worrying about how many games you have and play more games!

If you want to be really rude toward people who'd created GAs you decided to enter & you don't care about stuff like suspensions, then sure, go ahead.

you can hide your crappy games

Deleting something you won here is not only violation of the site rules (as I can understand you don't care about it), but also a dick move. I mean, it's a disrespect to the one who gifted you this game, and disrespect to other users who participated in it and wanted to win it. Delete it if you want, but don't forget that you insulted a shit ton of people by this.

Well, you could just hide the games in your library, no need to go nuclear on them.

If you really can't stand the idea of cluttering your library with stuff you don't want, hidden or not, then you can just stop caring, delete those wins, eat the inevitable suspension (which might even be permanent, at staff's discretion), and call it a day.

Pretty rude, both to the giveaway creators, kind enough to gift them to you, and to the other entries, since you denied their chances to win them.
Especially if they're actually good games that just aren't your cup of tea, rather than random shovelware. That's literally spitting on their faces.

After the suspension is over, the only tangible consequence will be the inability to pass most SGTools filters.
You'll also be getting a lot of blacklists - you're likely getting some already, just for stating your intention of deleting wins.

The "ethically correct" alternative is to get extra copies of the specific games, give them back to the creators, and let them reroll or delete the giveaways.
This way, you're effectively "resetting" those giveaways. Not as good as not entering them in the first place if you don't want them, but close enough.

However, this option could be unaivalable if the giveaway creators are offline - and some have been offline for periods ranging from 2 weeks to 2 years.
Not to mention it'd be outright impractical for multi-copy giveaways, reroll would be the only option in that case, and a pretty iffy one after so long.

Lastly, if you don't care about the site anymore, you could just delete the account.

Just hide the games like Oni suggested. In the library right click on the game -> manage -> hide this game (I'm not using english in the steam client so the names may vary). If you don't care about steamgifts any more you can also delete your SG account and after a year you're free to rejoin if want again.

When you delete a game that you won on SG, the system doesn't know if the giver didn't gift the game or if the receiver just deleted it. If you remove a game that you won, you are punishing the giver in order to feel better about your library--you are cheating them out of the CV they got when you clicked the "received" button when they did nothing wrong and upheld their end of the bargain
A FAR better way is to just hide the games you don't like, and then you won't ever see them and be tempted to play them. Also, if you remove games you paid for, and then a few years from now your tastes change and then you want to play them? You have to re-purchase them. OTOH, if you had just hidden them, you just unhide them.

Seems like it has weighed some on you, I would remove the games. I am curious how many games did you plan to remove that were won here 5-10?

Tu caso es curioso, varias veces hice giveaways pensando en los que menos juegos tenían y aunque considero que SG Tools es algo tedioso vale la pena en ocasiones. No te culpo si Pixel Cup Soccer no lleno tus expectativas porque el desarrollador prometió muchas cosas y hasta hoy no ha cumplido, si ese fuera el caso, mas que molestia por mi parte seria extrañeza. Para mi no hay gran perdida si lo eliminaras porque no gaste un peso, solo tiempo en Tremor Games (unos minutos diarios). Ahora si que habría que cumplir suspensiones como ya te lo comentaron y cuidado con cuantos borras.