Please contact your local waste disposal company for professional disposal. If necessary, ask your local town hall. You can find a (non-official) overview of municipal return points in Germany here: https://www.elektroschrott.de/wertstoffhoefe/
An overview of take-back points from the take-e-back system can be found here: https://www.take-e-back.de/Verbraucher-Ruecknahmestellen-finden
Appliance batteries and rechargeable batteries can be returned free of charge wherever they are sold - regardless of where they were purchased and regardless of brand and type. Even if you deliver the energy sources to the collection points of the municipalities (e.g. recycling yards) or to mobile pollutant collection points, you will of course not incur any costs. According to § 11 BattG, owners of used batteries must collect them separately from unsorted municipal waste. Used portable batteries are collected exclusively at collection points that are connected to the common take-back system or a manufacturer's own take-back system.
There are currently over 200,000 collection points in Germany. You are also welcome to return batteries to WEROCK Technologies. However, in the interest of sustainability we recommend the nearest collection point.
Further information is available at http://www.grs-batterien.de/start.html as well as from the GRS hotline on 01806 - 80 50 30 (20 cents/call from the German fixed network of Deutsche Telekom AG, prices may vary from mobile phone networks and from abroad).