Yes, it is possible to be self-exclude.

A nationwide self-exclusion allows you to permanently exclude yourself from all online casinos, all land-based casinos in Switzerland, as well as the online offerings of Swisslos and La Loterie Romande. The exclusion also applies to all casinos in Liechtenstein.

Under My Account > Responsible Gaming you can apply for a nationwide ban. You also have the option of blocking yourself on App­li­ca­tion for vo­lun­ta­ry gamb­ling sus­pen­sion - Spielerschutz. No player account is required for this.

A self-exclusion is a protective measure and is indefinite. It can only be lifted under specific conditions and after a thorough review by the appropriate authorities.