Please suggest to me a good watermark easy soft. I would like to regulate watermark transparency on my images.
In any serious multilayer photo editing program you can make a watermark image or text in a new layer and then adjust that layer partially transparent (=reduce the layer opacity). A flattened version of the image = your watermarked version. Try Krita if you need freeware.
There exists free software which can add a watermark to every image in a folder. If you need it, check for ex. IrfanView.
How to make existing watermarks fully transparent or otherwise restore the underlying image? This question surely is also interesting for many people. In this site it probably will be closed soon because it's easily considered as asking help for criminal actions. But one workaround software for that trick exists. It's a banking application. Pay with it the price of the image and you'll get a watermark free version.