Right-clicking the clip, in the sequence, and DELETEing it will create a precise hole that's the same size as the removed clip.
If the media clip was used in full, just drag it back into that hole. It should snap into place. (Use a right-click|CLOSE gap to remove holes.)
To simply remove an effect, select the clip, then right-click|EFFECTS. That will bring it up in the effects window. Click the X to the right of the name of the effect that you want to delete. Then SAVE.
To get a closer look at a clip, click the CLIPS menu. The timeline can be expanded horizontally by using the "zoom" slider at the right-bottom of the edit window..
Another way to expand the timeline - vertically - is to place the mouse pointer on the 5 dots at the middle-bottom of the video timeline. A double-headed arrow appears. Drag it downwards.