Rip the old shower sealer away from the wall, using a putty knife to wedge in between the two to help break the seal of the old adhesive.
Dampen a rag with enough adhesive residue remover so that it is wet but not dripping.
Remove all excess adhesive that remains on the wall with the rag, adding more adhesive remover as necessary. Use the putty knife on especially stubborn chunks to clean the wall completely.
Wash the wall thoroughly with a clean rag dipped in warm, soapy water.
Dry the area completely using a soft cloth.
Apply a line of silicone caulk down the wall where the old sealer strip was.
Press a new glass shower door sealer directly over the silicone caulk. Push down hard to bind the sealer to the wall.
Wipe away excess caulk that was pushed out the sides of the sealer.
Allow the silicone caulk to dry for 48 hours before using the glass shower.