onKeyDown = e => {
    if (e.keyCode === 8) {
      console.log("delete");
    }
  };

   <Select
              className={classes.queryBuilderContainerItem}
              classes={classes}
              styles={selectStyles}
              options={this.state.suggestions}
              components={components}
              value={this.state.single}
              disableUnderline={true}
              disabled={true}
              onChange={this.handleChange("network")}
              placeholder="Search a to do"
              onKeyDown={this.onKeyDown}
            />